In general, this project will investigate fluoride nutrition and metabolism and calcified tissue metabolism. Among the specific investigations are: (1) Determination of the dietary source of fluoride for infants, toddlers and young adults in the United States based on Market Basket Collections of the F.D.A. This will include several cities in the same dietary region and continuation of a longitudinal study in selected cities; (2) The interrelation of fluoride with Vitamin A and E will elucidate (a) the role of Vitamin A in bone, the possible effects of fluoride on glycosaminoglycan metabolism and distribution in bone and (b) the effect of fluoride on the absorption of Vitamin E and levels in plasma and tissues; (3) Further studies of the interrelation of fluoride with other trace elements (i.e. aluminum, iron, and zinc); (4) Characterization of the major nonionic fluoride excretion product(s) obtained after the administration of perfluorooctanoic acid to rats and also the nonionic fluoride in plasma of rats given high inorganic fluoride intake; (5) The development of a PTH immunoassay for rats; (6) Investigation of biological parameters in a long established mouse colony which has been provided a low F diet and a low or high fluoride water supply and (7) An investigation of the effect of fluoride on the alveolar bone loss in STR/N mice.